1. Field of the Invention
This invention relates generally to concrete building structures and more particularly is directed to an improved method and apparatus for precasting concrete building elements in vertical molds and to a building construction utilizing as the principal structural elements a plurality of similar concrete L-shaped wall units and flat roof slabs precast thereby.
2. Description of the Prior Art
In order to reduce labor cost and save time in erecting and dismantling the forms required in poured concrete wall and roof construction, various means and methods have been devised to precast concrete wall units usually at remote manufacturing facilities requiring expensive equipment as well as costs for transporting and handling the precast units in delivery to the building site. Although precasting has been performed in molds disposed both horizontally and vertically, both methods require in excess of twelve hours for the concrete to be sufficiently cured to permit vertical lifting out of the mold for the latter's reuse. Steam curing and/or use of additives to the concrete mix reduces this time to between six to eight hours, but is a much more costly procedure.
Likewise, to reduce building costs and improve efficiency, particularly in erecting bungalow type single family dwellings, various units, precast and prefabricated as entire room units, entire wall units, made in a wide variety of sizes and configurations, as segmental units and as individual panels, have been proposed and used. Each of these units has its own disadvantages and drawbacks, including requirements for costly manufacturing plant facilities, special on site erecting equipment and transportation means from point of manufacture. There is, therefore, a need, particularly in low cost housing, which this invention satisfies, for a durable concrete building capable of being erected by taking advantage of the economy of precast units while eliminating costly plant and transportation facilities and also having an inexpensive system for assembling the precast units into a completed structure.